Stator lamination iron losses heretofore have dominated energy dissipation in most dynamoelectric machines. There is therefore a need to increase the efficiency of dynamoelectric machines particularly with respect to stator iron losses.
Amorphous ferromagnetic material (AFM) lacks crystalline structure and has about one-tenth the iron losses of common crystalline iron alloys. It is formed in a sheet roughly 1 mil thick, (as compared to 12-14 mils of common electrical steels) with a hardness in the range of 63-70 Rockwell C, like many tool steels, so that it is machined only by grinding, electric discharge machining or lasers. Such machining risks heat-inducing crystal formation and magnetic performance degradation. AFM may be slit and sheared economically. Punching of AFM, as for stator laminations, is impractical due to material hardness and very thin sections. Iron losses in dynamoelectric machines can also be reduced with thin section (under the usual 12-14 mils) electrical steels, most commonly silicon alloyed, which are more readily fabricated than are AFMs.
Sims, in U.S. Pat. No. 3,983,435, enunciated several dynamoelectric machine stator structures formed from a folded ferromagnetic strip. In several of Sims' configurations the stator poles or teeth are formed of the strip folded in a variety of ways, all having the plane of the folded strip disposed generally parallel to the dynamoelectric machine longitudinal axis, and the yoke or "back iron" being formed of an unfolded plane strip edge wound so that the plane of the strip is disposed generally normal to the machine longitudinal axis.
Stanley, in U.S. Pat. No. 4,395,815, describes a process of forming stator structures from an edge wound strip. The stator slots are notched from a single edge of the ferromagnetic strip, leaving poles, and the remainder of the strip, which is to form the yoke or back iron, is axially deformed along one edge by regularly spaced depressions or deformations, extending partially across the yoke or back iron portion of the strip, to cause the strip to turn in its own plane.